I'm using the water-to-water heat pump models HeatPump:WaterToWater:EIR:Heating and Cooling in simple hot and chilled water loops connected to a fancoil. The water temperatures and mass flow rates in both loop nodes look fine. I got good values for the outputs of the heat pump when I used the constant performance curves in the example file for this model. But when I have started using curves with values, I have started having a mess with the model results.
The EIR modifier function of temperature curve (EIRFT)
The EIRFT curve should use the Outlet hot/chilled water temperature as "Input variable 1". However, when I look at the output variable "Performance Curve Input Variable 1 Value" for this curves, I'm not obtaining the expected value.
I think this curve is getting as input the PLR value instead. Although the water-to-water heat pump PLR is not available for reporting, the value I'm getting as "input variable 1" matches "PLR=Load Side Heat Transfer Rate / (Reference Capacity*CAPFT)".
The "Performance Curve Input Variable 2 Value" output works well, and the curve output is consistent with the reported input values.
The EIR modifier function of PLR curve (EIRFPLR)
I get 0 as both input and output value when I report the curve output variables. I make changes in this curve and the heat pump outputs (electric power and source side heat transfer rate) remain the same although the heat pump isn't working at full load (PLR<1).
The model equations
I couldn't find the model equations in the Engineering Reference Manual for this object. I guess they are the same as the EIR-based chiller model:
Power consumption = CAPref* CAPFT * (1/COPref) * EIRFT * EIRFPLR * Cycling Ratio
Cycling Ratio = PLR / PLRmin (I assumed PLRmin=1 because there is no input for PLRmin)
I couldn't actually check whether I'm getting consistent results, because the reported "EIRFPLR" output value is 0. However I have all the other values, so I tried to solve for it. The EIRFPLR value I found turned out to be exactly the expected EIRFT value for the correct input variables (not the reported ones).
Error with EIRFT table dimensions and transition version
Maybe this other issue is related. In version 9.1 this heat pump model accepted a "Table:TwoIndependentValues" object as EIRFT curve. In version 9.2, it doesn't accept the equivalent "Table:Lookup" object with two independent variables (although it does accept the biquadratic curve of the example file). I get the following Severe/Fatal Error:
* Severe * Table:Lookup "EIRCURVEFUNCTEMP": Target and Gridded Data do not have the same dimensions.
I also had an issue with this heat pump model using the Transition version tool from v9.1 to v9.2. I got an error about the minimum number of fields of these objects. In the .idd file of both versions the \min-fields value is set to 15, while the number of fields is actually 14. I solved it by changing this number in the corresponding .idds manually, then the tool worked.
Conclusion
Did you observed this problem with the performance curves of the HeatPump:WaterToWater:EIR:Heating model? Is it only an issue with the reported output variables, or is the model producing bad results?
I would be grateful if somebody could confirm if the HeatPump:WaterToWater:EIR:Heating equations are equivalent to the ones of the EIR chiller model. Thank you for your help!
